Fat crystallization process



Ohio No Drawing. Filed Sept. 21, 1961, Ser. No. 139,608

Claims. (Cl. 260-428) This invention relates to an improved crystallization process. More particularly, it relates to the addition of certain crystal modifying agents to glyceride oils containing fatty materials which are insoluble in the oils, whereby separation of the insoluble fatty materials from the oils is facilitated.

A large amount of vegetable glyceride oil is used as salad oil. Such oils can serve as a base for various liquid salad dressings, providing an oily coating for salad ingredients. They are also used in mayonnaise emulsions. Both salad oils and mayonnaise are usually kept under refrigeration by the housewife. At temperatures of about 40 F. or lower, fatty materials will deposit out of many salad oils, causing them to have a cloudy appearance. In mayonnaise, such crystal formation tends to break the emulsion, causing separation of fatty material from the aqueous portion.

If soybean oil is used as a salad oil it tends to develop a characteristic beany odor and flavor. Even when it has been rendered completely odorless and fiavorless by high-temperature steam deodorization, the characteristic odor and flavor will return, in part, at least, due to the linolenic acid content of the oil.

It has been proposed that the stability of soybean oil against odor and flavor reversion can be increased by hydrogenation. However, hydrogenation decreases the unsaturation of unsaturated component fatty acids and also converts the unsaturated acids to higher-melting and lesssoluble isomers. The oil must then be winterized by a process including cooling and subsequent separation of insoluble glycerides to remove materials which will solidify when the oil is refrigerated, and thereby cause undesirable salad oil performance and appearance. Other oils such as cottonseed oil are given a similar Winterizing treatment. Insoluble fatty materials in oils such as corn oils are also removed by a cooling step, followed by a separation step.

Another important use of glyceride oils is in the paint industry. Oils of particular interest are the so-called drying oils which form protective coatings because of the ability of these oils to polymerize or dry after they have been applied, thereby forming tough, adherent, impervious and abrasion-resistant films.

It is generally believed that the film-forming properties of drying oils are related to their degree of unsaturation, and that the films are formed by polymerization of double bonds present in unsaturated oils. It is highly desirable, therefore, that oils suitable for use as drying oils contain a large amount of triunsaturated glycerides, and relatively few trisaturated glycerides or mixed saturated-unsaturated triglycerides.

U.S. Patents 2,442,531 and 2,442,533, issued to E. W. Eckey on June 1, 1948, disclose the directed rearrangement of triglycerides. By means of the process disclosed in these patents a substantial portion of mixed saturated- 'unsaturated triglycerides is rearranged to form a larger proportion of highly saturated glycerides and highly unsaturated glycerides. The more saturated glycerides in crystalline form are then separated from the rearranged mixture, leaving an unsaturated oil very suitable for use as a drying oil.

Special coating fats are required for coating of candies.

States Patent 3,059,010 Patented Oct. 16, 1962 These fats must have a high melting point so that they will not be greasy at normal room temperatures. However, these fats must also melt in the mouth when the candy is eaten, and thus the presence of fats melting at too high temperatures are undesirable. When oils such as hydrogenated palm kernel oil, and palm oil, either hydrogenated or unhydrogenated, are to be used for this purpose, it may be desirable to separate out highly-saturated materials which would produce a Waxy taste in the mouth. Suitable confectioners fats can also be formed from the more saturated portions of directed rearranged triglycerides.

At times it would be desirable to use palm oil as a major constituent of a margarine oil. In certain geographic locations palm oil is cheaper than other oils, and a supply of palm oil may be more readily available than a supply of some other oil. It has been found that the content of high-melting insoluble fats in palm oil, at a temperature of 92 F., is too high to produce a satisfactory margarine, since these insoluble fats will impart a waxy taste in the month during eating. Separation of the insoluble fats from the palm oil would increase its utility as a margarine constituent.

One of the main problems encountered in the separation of insoluble fatty materials from glyceride oils has been the fact that the insoluble fatty materials entrain a large amount of glyceride oil. In addition, conventional separation procedures are very low.

It has now been found that by the process of this invention the separation of insoluble fatty materials from liquid glyceride oils is greatly facilitated, thereby permitting the recovery of a much larger amount of liquid oil than has heretofore been possible. In addition, the rate of separation is greatly increased. As used herein the term insoluble fatty materials is intended to include materials which dissolve in oils at elevated temperatures and which will precipitate out of solution as the oils are cooled and allowed to stand.

It is therefore an object of this invention to provide a process for modifying insoluble fatty materials in glyceride oils whereby the subsequent separation of the fatty materials is greatly facilitated.

It is a further object of this invention to provide an improved process for making a salad oil.

Another object is to provide an improved method of making a drying oil.

Yet another object is to provide a method of making confectioners fats which have good eating quality.

Other objects and advantageous features will be apparent from the following detailed description.

In general, the process of this invention comprises the steps of dissolving in a glyceride oil containing insoluble fatty material, at a temperature at which substantially all of said fatty material is in solution in said glyceride oil, from about 0.001% to 0.5%, by weight of oil, of sucrose esterified with an average of at least one saturated fatty acid having from 12 to 22 carbon atoms in the alkyl chain, at least one short-chain fatty acid having from 1 to 6 carbon atoms in the alkyl chain, the total short-chain fatty acid content being equal to from 5% to by weight of the total long-chain fatty acid content; cooling the glyceride oil to a temperature at which insoluble fatty material comes out of solution; and separating the insoluble fatty material from the oil. The degree of esterification should be such that the ester contains an average of not more than about 5 unesterified hydroxyl groups per sucrose molecule. Esters containing more than that number of unesterified hydroxyl groups will be too insoluble to modify the fatty materials in the desired manner.

The sucrose ester exerts a modifying effect on the insoluble material so that it comes out of solution in the form of large crystalline aggregates. These entrain a or fatty acid halides.

' of sucrose monopalmitate. V age of two acetyl and one palmitoyl groups per molecule smaller amount of liquid fatty .glycerides during separation than do crystals formed in the absence of ester.

The process of this invention is generally applicable to any glyceride oils which contain fatty materials which will dissolve in the oils at elevated temperatures and which will crystallize out of solution when the oils are subsequently cooled and allowed to stand. For example, the removal of insoluble fatty materials from oils which are conventionally winterized? to form salad oils, such as cottonseed oil, hydrogenated soybean oil, and corn oil is greatly facilitated. The process can be applied to oils such as palm oil and palm kernel oil, either hydrogenated or unhydrogenated to form improved margarine oils or confectioners fats.

Directed rearranged triglycerides can also be processed by this invention. Preferably the directed rearrangementis carried out as described in US. Patent 2,442,531, issued June 1, 1948, in which triglyceride oils are contacted with a low-temperature molecular rearrangement catalyst at such a temperature that the. more highly saturated triglycerides are precipitated as they are formed during the rearrangement of the glycerides in the oil. A list of. suitable rearrangement catalysts is set forth in the aforementioned U.S. Patent 2,442,531. However, it is to be understood that other suitable rearrangement catalysts and operating conditions can .be used. As used herein theterm directed rearrangement is intended to denote a molecular rearrangement process directed for a greater yield of highly saturated. and highly unsaturated glycerides than would be found in an oil having a random distribution of fatty acid triglycerides.

Thesucrose esters can be formed by direct esterification of sucrose with fatty acids, fatty acid anhydrides,

They can alsobe prepared by interesterification of sucrose with fatty acid esters of other polyhydric compounds in the presence of suitable solvents soluble fatty material is in liquid form prior to slowly cooling the oil in which is dissolved the sucrose ester. The ester can be added prior'to or after heating. The

exact conditions for cooling will vary with the amount of oil in the batch and the amount of insoluble fatty material, 'but the optimum cooling conditions can be deter- 'mined by those skilled in conventional oil graining procedure. p 7

The insoluble fatty materials are conveniently separated by conventional filtration procedures, but other methods of. separation such as centrifuging, can be used.

The improved results which can be achieved by the process of this invention. are clearly illustrated by the following examples:

EXAMPLE I 250 gfof refined and bleached soybean oil, hydrogenated to an iodine value of about 105, was mixed in a container with 0.1%, by weight of oil, of sucrose diacetyl monopalmitate. This ester was the reactionprodnet of 1 molecule of acetic anhydride and 1 molecule The ester contained an averof sucrose. p

The mixture of oil and additive was heated to 140 F.

iforone hour. Itwas then placed for 3 days in a room held at a temperature of140 F. The resulting mixture of liquid and solid glycerides which had formed was filtered through a Biichner funnel using filter paper and suction. The following measurements were recorded of 'the total amount of oil passing through the filter at various and then holding it at 40 F. for three days.

time intervals, as compared with a similar sample containing no additive:

Filtrate Volume (00.)

Time (min.) Sucrose No Additive acetyl V palmitate 1 71 so 2 V 7 112 "144 150 m p 146 157 The iodine value of the two filtrates were substantially the same, showing that the increased filtration was due to crystal modification and not a decrease of amount of crystals. 7

As can be seen by the above data the addition of sucrose fatty ester increased the filtrate volume, cleanly demonstrating the increase in yield which can be obtained by addition of sucrose fatty ester prior to cooling the hydrogenated soybean oil.

A comparable improvement in separation can also be obtained by substituting in the example esters containing myristic, stearic, arachidic or behenic acid, or mixtures of these acids in combination with or in place of the palmitic acid, and additionally, butyric, propionic, valeric or caproic acids and mixtures thereof in combination with or in place of the acetic acid. In general, a decrease in the number of unesterified hydroxyl groups will result'in improved results.

EXAMPLE II "An ester of sucrose containing an average of about four acetic acid groups and aboutfour palrnitic acid groups per molecule of sucrose 'was dissolved in a onepound sample of refined cottonseed oil at a level of 0.005% by weight. This oil, and also a'sample of the oil without" ester, were heated to a temperature of F. with stirring. The samples were allowed to cool gradually and held at 50 F. for about three days and then were cooled to 40 F. and held at that temperature for about 24 hours to insure complete crystallization; Each sample was vacuum filtered using a Biichner'funnel and filter paper. The filtration was continued until the filter cake broke. The filtrates were weighed and the yields of oil calculated. These data'were as follows:

Amt. Additive (percent) Filtration Yield of on Yield of on Time (min) (gin) (percent) None 265. 0 296 66.2 0.005 112.5 305 68.2

EXAMPLE III Soybean oil was hydrogenated to an iodine value of 105 and winterized by holding it at 50 F. for 2 weeks The oil was then vacuum filtered. -A mixture was formed containing 95% of the clear oil filtrate and 5% of a saturated triglyceride containing about 2 palmitic acid groups and 1 stearic acid group per molecule. This saturated triglyceride had an iodine Value of 0.012. To. the mixture was added 0.1%, by weight, of the sucrose ester of Example I. 250 gm. samples of the'oil mixture with and without added ester were heated to 140 F. for one hour to destroy all crystal nuclei and then cooled to 80 F. and held at that temperature for three days to permit crystals to form. The resulting mixtures of insoluble fatty material and glyceride oil were filtered through a Btichuer funnel using filter paper and vacuum. The following measurements were recorded of the total amounts of oil passing through the filter at various time intervals:

1 Not measured.

Comparable results will be achieved by substitution in the foregoing example of oils such as directed rearranged glyceride oils, hydrogenated vegetable oils and other glyceride oils containing fatty materials insoluble in these oils at higher temperatures.

Although it is to be understood that the invention is not to be limited by any theory, it is believed that esters suitable for improving the filtration of oils for the purpose of separating insoluble fats from oils should contain a substrate-similar and a substrate-dissimilar moiety in the molecule. In the case of the aforementioned systems fatty acid chains in the fats and in the sucrose ester are similar. The sucrose portion of the additive represents a polyhydric compound which is dissimilar from that of the fats.

It is also believed that it is important that materials added as filtration aids bear some relation in melting point and/or solubility to the fats which are to be separated by filtration. These aids should be made with fatty acids having neither too high nor too low a melting point, so that the modifier will have a tendency to deposit on the incipient crystal nuclei as they are formed, thereby modifying the fat crystals. This results in the formation of crystal aggregates (around a crystallization center) which are compact and not feathery and are more easily filtered.

Further, it is believed that if the additive has too high a meln'ng point or too low a solubility in the oil, nuclei of additive will tend to form before the fat nuclei are formed, and the additive may act as a nucleating agent for the fat, forming more nuclei than would normally appear in the fat. As a result the fat crystal aggregates will be more numerous and filtration will be more difficult.

Although specific examples have been given to illustrate the invention, it is to be understood that the invention is not to be limited to these examples, and that variations in the processing conditions which will suggest themselves to those skilled in the art are intended to be Within the scope of the invention. it will further be appreciated that sucrose esters used in the practice of this invention usually will be a mixture of various esters and that the specified proportions of fatty acids represent average values for such mixtures.

This is a continuation-in-part of application S.N. 845,- 641, filed October 12, 1959.

What is claimed is:

1. The method of separating insoluble fatty material from glyceride oil which comprises the steps of dissolving in said glyceride oil, at a temperature at which substantially all of said fatty material is in solution, from about 0.001% to 0.5 by Weight of oil, of sucrose esterified with an average of at least one saturated fatty acid having from 12 to 22 carbon atoms in the alkyl chain, at least one short-chain fatty acid having from 1 to 6 carbon atoms in the alkyl chain, the total short-chain fatty acid content being equal to from 5% to by weight of the total long-chain fatty acid content, said ester containing not more than 5 unesterified hydroxyl groups; cooling the glyceride oil to a temperature at which insoluble fatty material comes out of solution; and separating the insoluble fatty material from the oil.

2. The method according to claim 1 wherein a solution of sucrose ester in oil is heated to a temperature at which substantially all of the insoluble fatty material is dissolved, the sucrose ester is dissolved in said heated oil, and the resulting mixture is slowly cooled to a temperature at which fatty crystals will form.

3. The method according to claim 1 wherein the oil is heated to a temperature at which substantially all of the insoluble fatty material is dissolved, the sucrose ester is dissolved in said heated oil, and the resulting mixture is slowly cooled to a temperature at which fatty crystals will form.

4. The method according to claim 1 wherein the sucrose ester is an acetyl palmitoyl sucrose.

5. The method according to claim 1 wherein the oil is cottonseed oil.

6. The method according to claim 1 wherein the oil is hydrogenated soybean oil.

7. The method according to claim 1 wherein the oil is a directed rearranged glyceride oil.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE METHOD OF SEPARATING INSOLUBLE FATTY MATERIAL FROM GLYCERIDE OIL WHICH COMPRISES THE STEPS OF DISSOLVING IN SAID GLYCERIDE OIL, AT A TEMPERATURE AT WHICH SUBSTANTIALLY ALL OF SAID FATTY MATERIAL IS IN SOLUTION, FROM ABOUT 0.001% TO 0.5%, BY WEIGHT OF OIL, OF SUCROSE ESTERIFIED WITH AN AVERAGE OF AT LEAST ONE SATURATED FATTY ACID HAVING FROM 12 TO 22 CARBON ATOMS IN THE ALKYL CHAIN, ATT LEAST ONE SHORT-CHAIN FATTY ACID HAVING FROM 1 TO 6 CARBON ATOMS IN THE ALKYL CHAIN, THE TOTAL SHORT-CHAIN FATTY ACID CONTENT BEING EQUAL TO FROM 5% TO 100% BY WEIGHT OF THE TOTAL LONG-CHAIN FATTY ACID CONTENT, SAID ESTER CONTAINING NOT MORE THAN 5% TO 100% BY WEIGHT OF COOLING THE GLYCERIDE OIL TO A TEMPERATURE AT WHICH INSOLUBLE FATTY MATERIAL COMES OUT OF SOLUTION; AND SEPARATING THE INSOLUBLE FATTY MATERIAL FROM THE OIL. 